When the Giants play at AT&T Park, fans on the Peninsula flock to Caltrain, turning the typically staid commuter railroad into a rolling version of a tailgate party - minus the grill but with plenty of liquid refreshment, loud pregame enthusiasm and orange-and-black clothing.

Caltrain officials not only welcome the thousands of extra riders but also promote the service as the best way to get to the ballpark, and have added Giants Special trains after games. The number of riders on game days is up about 11 percent over last year. During July, the commuter railroad carried about 7,400 extra riders on game days, meaning about 3,700 fans took the train to and from the park.

"By and large, people love it," said Mark Simon, a Caltrain spokesman. "If you live on the Peninsula and you don't take Caltrain to the game, you're out of your mind."

Taking to Twitter

But some regular Caltrain commuters are not so enthusiastic. They complain that the flood of baseball fans overwhelms the train, making it hard to find a seat, crowding the aisles and destroying the usual tranquillity of their homeward commutes.

Many of their complaints are delivered not by phone, e-mail or in person but via social media outlets - particularly Twitter. Consider some of the following tweets from grumpy commuters during the team's most recent homestand.

"Oh, God. Giants game means Caltrain will be packed with loud people," complained someone using the moniker El Ingeniero.

"Giants games and Caltrain do not combine well," proclaimed Tim Cederman-Haysom.

Simon said Caltrain officials are aware of the tweets, and acknowledged that "some regular passengers are not always happy with Giants fans." He said Caltrain tries to educate game-goers on proper train etiquette through announcements and an online video that advises them to keep their feet off the seats, pick up their trash and respect other passengers.

No alcohol after 9 p.m.

Caltrain, which allows passengers to drink alcoholic beverages onboard, has also banned drinking on southbound postgame trains (and trains after other special events) after 9 p.m. in an effort to tone down postgame rowdiness from revelers eager to keep the party going.

"That's had a real positive effect," Simon said. "People used to stop at Safeway after the game and buy a 12-pack for the ride home. It has reduced that."

When drunk and disorderly fans are causing trouble or fights break out, Caltrain typically alerts its police force, which meets the train at the next station. Offenders are removed from the train and either arrested or left stranded at the station.

"That tends to leave an impression on people," he said.

On a game-day express from Palo Alto during the recent homestand, fans in Giants gear and regular commuters, many wearing work clothes, filled all but a few seats. The mood was festive and friendly, with many of the fans engaged in loud conversations punctuated by frequent laughter. Lots of fans, and at least a few of the commuters, drank beer, and one group brought along aluminum trays of food for a pregame feast.

Ron Cohen of Palo Alto, riding with his wife, Aileen, and son, Erik, 8, said they usually take Caltrain to the half-dozen games they attend each season and enjoy it far more than driving.

Best way to travel

Other fans said the convenience of being dropped a block from the ballpark, not having to find parking or sit in traffic and not having to worry about drinking and driving convinced them that the train is the best way to travel on game days.

"It's so convenient," said Michael Davis of Sunnyvale, sipping on a beer. "Why not do it?"

While some regular riders glowered a bit at the Giants fans, most seemed to tolerate the noisier-than-usual commute without complaint. Sarah Chirico, headed home to San Mateo from her job in the Stanford genetics department, said she's not really bothered by the noise but the crowds make it tough for her to be sure she can take her bike on board.

Checking the schedule

"I've been left behind three times," she said. "So now I look to see when there are Giants games and leave my bike at home."

But another Caltrain regular, Gina Kimura, a radiology technician in Palo Alto, said the vibe created by game-bound fans livens up her ride home.

"The cars are packed, really packed," she said. "But it's fun to see people going to the game, fun to see people excited."

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